This invention relates to a digital cordless telephone system for connecting mobile telephone terminals or digital cordless telephone sets to a public telephone network.
A conventional digital cordless telephone system of the type described comprises a plurality of radio stations which are classified into a master station and slave station or slave stations. Each slave station is connected to the master station in order to be operated in synchronism with the master station.
Each of the master and the slave stations is connected through an exchange station to the public telephone network and converts a received signal from the exchange station into a TDMA signal which is divided into a sequence of frames and which is transmitted from the radio station. In addition, each of the radio stations has a service area and can communicate with the mobile telephone terminals which are located in the service area. The service area has at least one common area adjacent to service areas in order that the mobile telephone terminals may be able to move from one service area to another in the course of communication.
Herein, it is to be noted that the master station supplies radio frame synchronization signals to the respective slave stations so as to operate the slave stations in synchronism with the master station. The radio frame synchronization signals are received by the slave stations with delay times which are different from one another and which are decided by a distance between the master station and each of the slave stations.
On setting up the conventional digital cordless telephone system, a delay time measuring apparatus should be prepared so as to measure the delay times. Such measurement of the delay times not only brings about an increase of costs but also is laborious and time-consuming.